1. Field of the Invention
The present invention relates to a magneto-optical type optical switch for light on/off control and optical path change in the fields such as optical communications and measurement. More particularly, the invention relates to a reflective optical switch that ensures size reduction and higher performance through a reflective configuration in which there is provided an input/output port portion with a number of fibers at one end of an optical switch functional unit so as to allow for a light beam to couple with different fibers after a round trip through the optical switch functional unit.
2. Description of the Related Art
Optical switches are optical devices having the optical path switching capability—typically to output input light from the input port to an arbitrary output port selected from among different output ports. The most basic form is 1×2 type (one input with two outputs), with various other systems and configurations developed today.
It is essential that an optical switch for optical communications be polarization independent, and among those meeting this requirement is a configuration in which a plurality of optical components such as birefringence elements, wave plates or Faraday rotators are arranged for use as an optical switch functional unit, with an input port portion provided at one end portion of the optical switch functional unit and an output port portion provided at the other end portion. The optical switch functional unit controls an external magnetic field applied by mechanically moving a permanent magnet or by an electromagnetic method, thus changing the polarizing direction and achieving optical path switching.
However, conventional optical switches have input and output port portions arranged opposed to each other at both end portions of the optical switch functional unit, making it necessary to use a number of optical components and arrange the components in a line. This has led to not only a high price but also a large size (long size).
In the case of a configuration that switches movable portions by a mechanical drive portion, on the other hand, there is a possibility that characteristic deterioration may occur as a result of chipping or wear, and furthermore the switching speed is slow.